Fuel or DEF dispenser having fluid temperature conditioning and control system

ABSTRACT

A fluid dispenser has a housing in which fluid flow control components are located and at least one fluid conduit completing first and second fluid flow paths between the at least one fluid storage tank and a nozzle coupled to the housing. The fluid dispenser also has a fluid flow meter located along said fluid flow path, a control system, and a recirculation subsystem. The recirculation subsystem has a bypass valve located along one of the first and second flow paths. The bypass valve is operative to prevent fluid communication between the first and second fluid flow paths when the fluid dispenser is in use and to allow fluid communication between the first and second fluid flow paths when the fluid dispenser is not in use. Methods of measuring the flow rate of a fluid in the fluid dispenser are also disclosed.

CROSS-REFERENCE TO A RELATED APPLICATION

The present application is a continuation of copending U.S. patentapplication Ser. No. 12/843,976, entitled “Fuel or DEF Dispenser HavingFluid Temperature Conditioning and Control System,” filed on Jul. 27,2010 and which is incorporated herein by reference in its entirety forall purposes.

FIELD OF THE INVENTION

The present invention relates generally to fuel dispensers, dieselexhaust fluid dispensers, and other such dispensers. More specifically,the invention provides a system for temperature conditioning and controlof a fluid, such as liquid fuel or diesel exhaust fluid, in a fluiddispenser.

BACKGROUND

Various countries have environmental regulations for vehicles whichlimit emissions of certain compounds, such as nitrogen oxide. Forexample, some regulations require that many newly-manufactureddiesel-powered vehicle engines significantly reduce nitrogen oxidelevels. One technology addressing this concern is selective catalyticreduction (SCR), which involves dosing a reductant into engine exhaustupstream of a catalyst to convert nitrogen oxides into less harmfulbyproducts. Diesel exhaust fluid (DEF) is a generic term for a reductantthat may be used in the process of SCR. An example of a common reductantis a 32.5% solution of aqueous urea.

Because many manufacturers have adopted SCR technology, SCR systems willoften be installed on new diesel vehicles. Correspondingly, dieselvehicles may now incorporate special DEF tanks, and DEF dispensers areincreasingly provided in retail service station environments.

However, DEF will crystallize and freeze at a relatively hightemperature (approximately 12° F.) compared to liquid fuels such asgasoline. In addition, DEF expands approximately 7% when frozen. Thisexpansion can cause damage to the internal components of a DEFdispenser.

One prior art solution to this problem involves mounting a 750 W/120Velectric heater in a DEF dispenser's lower hydraulic cabinet adapted toturn on when the ambient temperature in the cabinet reaches a specifiedlevel (e.g., 41° F.). Likewise, the solution may involve providing DEFdispensers with a retractable dispensing hose that is stowed in thedispenser's cabinet and a sliding cover or access door over thedispenser nozzle. Alternatively, the DEF dispenser may be adapted tosuspend operation if the ambient temperature in the hydraulic cabinetreaches 12° F. while the power is energized to prevent damage to thedispenser's fuel handling components.

Temperature effects have also presented problems in prior art liquidfuel dispensers. Liquid fuel dispensers are well known, and thesedispensers include flow meters that measure volumetric flow rate ofliquid fuel as it is dispensed. Such flow meters are typically requiredto comply with weights and measures regulatory requirements that mandatea high level of accuracy. This ensures that the customer is neitherovercharged nor undercharged for the purchase. Typically, eitherpositive displacement meters or inferential meters have been used forthis purpose.

The volume of liquid fuel is somewhat dependent on temperature (i.e., itexpands when heated and contracts when cooled). In addition, liquidfuels are typically sold by a volumetric measure, such as U.S. gallons.Prior art solutions provide temperature compensation by sending signalsfrom thermometric probes located in a flow meter to a first circuit inthe dispenser's lower fuel handling compartment, to a second circuit inthe dispenser's upper electronics compartment via an intrinsically safeconnection, and finally to a computation device designed to combine thetemperature data and pulser data. The computation device employs avolume correction factor to compensate the pulser data so as to accountfor temperature variations. Detailed information regarding temperaturecompensation of dispensed fuel is disclosed in U.S. Pat. No. 5,557,084to Myers et al., entitled “Temperature Compensating Fuel Dispenser,” theentire disclosure of which is incorporated herein by reference for allpurposes. However, this solution may not be available in many marketsdue to government regulation.

SUMMARY

According to one aspect, the present invention provides a fluiddispenser for installation in a forecourt in a fueling environment fordispensing liquid fuel or diesel exhaust fluid from at least one fluidstorage tank remote from said fluid dispenser into a vehicle. The fluiddispenser comprises a housing in which fluid flow control components arelocated and at least one fluid conduit completing first and second fluidflow paths between the at least one fluid storage tank and a nozzlecoupled to the housing. The fluid dispenser also comprises a fluid flowmeter located along said fluid flow path, a control system, and arecirculation subsystem. The recirculation subsystem comprises a bypassvalve located along one of the first and second flow paths. The bypassvalve is operative to prevent fluid communication between the first andsecond fluid flow paths when the fluid dispenser is in use and to allowfluid communication between the first and second fluid flow paths whenthe fluid dispenser is not in use.

According to another aspect, the present invention provides a fluiddispenser for dispensing liquid fuel or diesel exhaust fluid from atleast one fluid storage tank into a vehicle. The fluid dispensercomprises a housing in which fluid flow control components are locatedand a control system. The fluid dispenser also comprises a first fluidconduit completing a first flow path between the at least one fluidstorage tank and a nozzle coupled to the housing, and a second fluidconduit completing a second flow path between the nozzle and the atleast one fluid storage tank. Further, the fluid dispenser comprises abypass valve located along one of the first and second flow paths and atleast one controllable valve located along the second flow path. The atleast one controllable valve is in electronic communication with saidcontrol system.

In another aspect, the present invention provides a method of measuringthe flow rate of a fluid in a fluid dispenser for dispensing liquid fuelor diesel exhaust fluid to a vehicle in a fueling environment. Themethod comprises providing a fluid dispenser defining at least one fluidconduit connectable to first and second fluid flow paths between atleast one fluid storage tank and a nozzle coupled to the fluiddispenser. Also, the method comprises providing a control system,providing a fluid flow meter located along the first fluid flow path,and providing at least one controllable valve located along the secondfluid flow path. Further, the method comprises conditioning thetemperature of the fluid upstream of the fluid flow meter inside thefluid dispenser and selectively actuating the at least one controllablevalve to allow flowing fluid to flow to the at least one fluid storagetank when the fluid dispenser is not in use.

According to another aspect, the present invention provides a method ofmeasuring the flow rate of a fluid in a fluid dispenser for dispensingliquid fuel or diesel exhaust fluid to a vehicle in a fuelingenvironment. The method comprises providing a fluid dispenser comprisinga housing and a control system. The fluid dispenser defines first andsecond fluid conduits connectable to first and second fluid flow paths,respectively, between at least one fluid storage tank and a nozzlecoupled to the fluid dispenser. The method further comprises providing afirst controllable valve located along the first flow path and inelectronic communication with the control system. The first flow pathdefines a fluid inlet for an evacuation fluid downstream of the firstcontrollable valve. In addition, the method comprises providing arecirculation pump coupled to the second flow path and in electroniccommunication with the control system. Finally, the method comprisesclosing the first controllable valve and evacuating the fluid from thefirst and second fluid conduits when the fluid dispenser is not in use.

According to another aspect, the present invention provides a method ofmeasuring the flow rate of a fluid in a fluid dispenser for dispensingliquid fuel or diesel exhaust fluid to a vehicle in a fuelingenvironment. The method comprises the steps of providing a fluiddispenser comprising a housing and a control system. The fluid dispenserdefines first and second fluid conduits adapted for fluid communicationwith a nozzle. The first and second fluid conduits respectively completefirst and second flow paths through the fluid dispenser. The method alsocomprises providing a junction at which the first and second fluidconduits are in fluid communication with each other. The junction isspaced apart from the nozzle, and the junction defines an inlet forfluid communication with the at least one fluid storage tank.Additionally, the method comprises providing a valve in fluidcommunication with the inlet upstream of the junction and providing arecirculation pump coupled to the second fluid conduit. The valve andthe recirculation pump are in electronic communication with the controlsystem. Finally, the method comprises actuating the valve and therecirculation pump such that fluid recirculates through the housing whenthe fluid dispenser is not in use.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendeddrawings, in which:

FIG. 1 is perspective view of a prior art fuel dispenser for use in aretail service station environment.

FIG. 2 is a schematic illustration of a prior art fuel dispensing systemincluding the dispenser of FIG. 1.

FIG. 3 is a perspective view of a prior art DEF dispenser for use in aretail service station environment.

FIG. 4 is a schematic illustration of a fluid temperature conditioningand control system according to one embodiment of the present invention.

FIG. 5 is a schematic illustration of a fluid temperature conditioningand control system according to an alternative embodiment of the presentinvention.

FIG. 6 is a schematic illustration of a fluid temperature conditioningand control system according to a further alternative embodiment of thepresent invention.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made in detail to presently preferred embodimentsof the invention, one or more examples of which are illustrated in theaccompanying drawings. Each example is provided by way of explanation ofthe invention, not limitation of the invention. In fact, it will beapparent to those skilled in the art that modifications and variationscan be made in the present invention without departing from the scope orspirit thereof. For instance, features illustrated or described as partof one embodiment may be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

The present invention provides a system for temperature conditioning andcontrol of fluids in fluid dispensers. Embodiments of the presentinvention may be particularly adapted for use in dispensing DEF andliquid fuels, such as gasoline or diesel fuel. The terms diesel exhaustfluid and DEF are used broadly herein to refer to any reductant used toreduce nitrogen oxide emissions in vehicles, including ammonia and urea.To facilitate explanation of the preferred embodiments, a description ofexemplary prior art fluid dispensing systems is first provided below.

FIG. 1 is perspective view of a prior art fuel dispenser 10 adapted foruse in a retail service station environment. For example, fuel dispenser10 may be the ENCORE® S fuel dispenser sold by Gilbarco Inc. ofGreensboro, N.C.

Fuel dispenser 10 includes a housing 12 with a flexible fuel hose 14extending therefrom. Fuel hose 14 terminates in a manually-operatednozzle 16 adapted to be inserted into a fill neck of a vehicle's fueltank. Nozzle 16 includes a fuel valve. Various fuel handling components,such as valves and meters, are also located inside of housing 12. Thesefuel handling components allow fuel to be received from undergroundpiping and delivered through hose 14 and nozzle 16 to a vehicle's tank,as is well understood.

The fuel dispenser 10 has a customer interface 18. Customer interface 18may include an information display 20 relating to an ongoing fuelingtransaction that includes the amount of fuel dispensed and the price ofthe dispensed fuel. Further, customer interface 18 may include a mediadisplay 22 to provide advertising, merchandising, and multimediapresentations to a customer in addition to basic transaction functions.The graphical user interface provided by the dispenser allows customersto purchase goods and services other than fuel at the dispenser.

FIG. 2 provides a schematic illustration of a prior art fuel dispensingsystem in a retail service station environment. In general, fuel maytravel from an underground storage tank (UST) 28 via main fuel piping30, which may be a double-walled pipe having secondary containment as iswell known, to fuel dispenser 10 and nozzle 16 for delivery. Anexemplary underground fuel delivery system is illustrated in U.S. Pat.No. 6,435,204 to White et al., hereby incorporated by reference in itsentirety for all purposes.

More specifically, a submersible turbine pump (STP) 32 associated withthe UST 28 is used to pump fuel to the fuel dispenser 10. However, somefuel dispensers may be self-contained, meaning fuel is drawn to the fueldispenser 10 by a pump controlled by a motor positioned within housing12.

STP 32 is comprised of a distribution head 34 containing power andcontrol electronics that provide power through a riser pipe 36 down to aboom 38 inside the UST 28, eventually reaching a turbine pump containedinside an outer turbine pump housing 40. STP 32 may preferably be theRED JACKET® submersible turbine pump, manufactured by the Veeder-RootCo. of Simsbury, Conn. Also, STP 32 may contain a siphon that allows theSTP 32 to generate a vacuum using the force of fuel flow. In addition,riser pipe 36 and distribution head 34 may preferably be secondarilycontained to capture and monitor leaks. For example, such a system isdisclosed in U.S. Pat. No. 7,010,961 to Hutchinson et al., herebyincorporated by reference in its entirety for all purposes. There may bea plurality of USTs 28 and STPs 32 in a service station environment ifmore than one type or grade of fuel 42 is to be delivered by a fueldispenser 10.

The turbine pump operates to draw fuel 42 upward from the UST 28 intothe boom 38 and riser pipe 36 for delivery to the fuel dispenser 10.After STP 32 draws the fuel 42 into the distribution head 34, the fuel42 is carried through STP sump 44 to main fuel piping 30. Main fuelpiping 30 carries fuel 42 through dispenser sump 45 to the fueldispenser 10 for eventual delivery. Those of skill in the art willappreciate that dispenser sump 45, which may also be double-walled, isadapted to capture any leaked fuel 42 that drains from fuel dispenser 10and its fuel handling components so that fuel 42 is not leaked into theground.

Main fuel piping 30 may then pass into housing 12 through a product lineshear valve 46. As is well known, the product line shear valve 46 isdesigned to close the fuel flow path in the event of an impact to fueldispenser 10. U.S. Patent App. Pub. No. 2006/0260680 to Reid et al.,hereby incorporated by reference in its entirety for all purposes,discloses an exemplary secondarily-contained shear valve adapted for usein service station environments. The product line shear valve 46contains an internal fuel flow path to carry the fuel 42 from the mainfuel piping 30 to internal fuel piping 48, which may also bedouble-walled.

After the fuel 42 exits the outlet of the shear valve 46 and enters intothe internal fuel piping 48, it may encounter a flow control valve 50positioned upstream of a flow meter 52. In some prior art fueldispensers, the valve 50 may be positioned downstream of the flow meter52. The valve 50 may preferably be a proportional solenoid controlledvalve, such as described in U.S. Pat. No. 5,954,080 to Leatherman,hereby incorporated by reference in its entirety.

The flow control valve 50 is under control of a control system 54 via aflow control valve signal line 56. In this manner, the control system 54can control the opening and closing of the flow control valve 50 toeither allow fuel to flow or not flow through meter 52 and on to thehose 14 and nozzle 16. Control system 54 may be a microprocessor,microcontroller, or other electronics with associated memory andsoftware programs running thereon. Control system 54 typically controlsother aspects of the fuel dispenser 10, such as valves, displays, andthe like as is well understood. For example, the control system 54typically instructs the flow control valve 50 to open when a fuelingtransaction is authorized. In addition, control system 54 may be inelectronic communication with a site controller 56 via a fuel dispensercommunication network 58. The site controller 56 communicates withcontrol system 54 to control authorization of fueling transactions andother conventional activities. The site controller functions maypreferably be provided by the PASSPORT® point-of-sale systemmanufactured by Gilbarco Inc.

The flow control valve 50 is contained below a vapor barrier 60 in ahydraulics compartment 62 of the fuel dispenser 10. The control system54 is typically located in an electronics compartment 64 of the fueldispenser 10 above vapor barrier 60. After the fuel 42 exits the flowcontrol valve 50, it typically flows through meter 52, which measuresthe volume and/or flow rate of the fuel.

Flow meter 52 is typically a positive displacement or inferential flowmeter. Meter 52 typically comprises a pulser 66 that generates a pulseseries indicative of the volumetric flow rate of fuel and periodicallytransmits the pulse series to control system 54 via a pulser signal line68. In this manner, the control system 54 can update the total gallonsdispensed and the price of the fuel dispensed on the information display20.

As fuel leaves the flow meter 52 it enters a flow switch 70. The flowswitch 70, which is preferably a one-way check valve that preventsrearward flow through fuel dispenser 10, generates a flow switchcommunication signal via the flow switch signal line 72 to the controlsystem 54 to communicate when fuel is flowing through the flow meter 52.The flow switch communication signal indicates to control system 54 thatfuel is actually flowing in the fuel delivery path and that subsequentsignals from flow meter 52 are due to actual fuel flow.

After the fuel 42 enters flow switch 70, it exits through internal fuelpiping 48 to be delivered to a blend manifold 76. Blend manifold 76receives fuels of varying octane levels from the various USTs andensures that fuel of the octane level selected by the customer isdelivered. After flowing through blend manifold 76, the fuel passesthrough fuel hose 14 and nozzle 16 for delivery to the customer'svehicle.

In this case, fuel dispenser 10 comprises a vapor recovery system torecover fuel vapors through nozzle 16 and hose 14 to return to UST 28.An example of a vapor recovery assist equipped fuel dispenser isdisclosed in U.S. Pat. No. 5,040,577 to Pope, incorporated herein in itsentirety for all purposes. More particularly, flexible fuel hose 14 iscoaxial and includes a product delivery line 78 and a vapor return line80. Both lines 78 and 80 are fluidly connected to UST 28 through fueldispenser 10. Lines 78 and 80 diverge internal to dispenser 10 atmanifold 76, such that product delivery line 78 is fluidly coupled tointernal fuel piping 48 and vapor return line 80 is fluidly coupled tointernal vapor return piping 82. During delivery of fuel into avehicle's fuel tank, the incoming fuel displaces air in the fuel tankcontaining fuel vapors. Vapor may be recovered from the vehicle's fueltank through vapor return line 80 and returned to the UST 28 with theassistance of a vapor pump 84. A motor 86 operates vapor pump 84.Internal vapor return piping 82 is coupled to a vapor flow meter 88.Vapor flow meter 88, which measures vapor collected by the nozzle 16when fuel 42 is dispensed, may be used for in-station diagnostics andmonitoring or control of vapor recovery as is well known.

After the recovered vapor passes through the vapor flow meter 88, therecovered vapor passes to vapor line shear valve 90 (which is analogousto product line shear valve 46). Finally, the recovered vapor returns toUST 28 via vapor return piping 92. Vapor return piping 92 is fluidlycoupled to the ullage 94 of UST 28. Thus, the recovered vapor isrecombined with the vapor in the ullage 94 to prevent vapor emissionsfrom escaping to the atmosphere. The vapors recombine and liquefy intofuel 42.

FIG. 3 is a perspective view of a prior art DEF dispenser 100 for use ina retail service station environment. For example, dispenser 100 may bethe ENCORE® S DEF dispenser, sold by Gilbarco Inc. DEF dispenser 100 isin many respects similar to fuel dispenser 10 and comprises a housing102 containing fluid handling components. These fluid handlingcomponents allow DEF to be received from above- or below-ground pipingand delivered through hose 104 and nozzle 106 to a vehicle's DEF tank,as is well understood. In addition, DEF dispenser 100 comprises acustomer interface 108, information display 110, and media display 112analogous to those described above.

However, DEF is corrosive to some materials, such as aluminum and carbonsteel, and the purity of DEF must be maintained as it is dispensed.Thus, many DEF dispenser fluid handling components are plated or formedof stainless steel or composite plastic. One example of a hose 104 and anozzle 106 that may be utilized for dispensing DEF is the 21Gu™ DEFfilling system, sold by OPW of Hamilton, Ohio.

As explained above, DEF is known to have a relatively high freezingtemperature. Thus, fuel hose 104 is an automatically retractable hosethat is stored in a compartment of DEF dispenser 100 when not in use.Further, nozzle 106 is stowed in an insulated and/or heated nozzle boot114 that is enclosed by a slidable access door 116. When DEF dispensingis desired, a customer may slide the access door 116 upward so thatnozzle 106 and hose 104 may be extracted. Other prior art DEF dispensersmay employ “hanging” hoses and nozzles that are insulated to prevent DEFthat resides in the system while not in use from freezing.

Those of skill in the art will appreciate that the fluid handlingcomponents of a prior art DEF dispensing system are in many respectsanalogous to those of the prior art fuel dispensing system illustratedin FIG. 2. By way of additional background, however, a brief discussionof some notable differences between the two systems follows.

First, although DEF may be provided to DEF dispenser 100 from a UST, itmay also be delivered from an above-ground tank, such as an intermediatebulk carrier (IBC) or a larger “skid tank.” In such a case, DEF may bedelivered to the dispenser 100 via above-ground piping, which may beinsulated and/or heated. Both wet-pit (i.e., submersible) and dry-pitpumps may be used to deliver DEF from the tank DEF dispenser 100.

Embodiments of the present invention provide a system to conditionfluid, including both liquid fuel and DEF, to be dispensed to a desiredtemperature and maintain this temperature even while dispensing is notongoing. Thereby, a fluid dispenser may both obtain an accuratemeasurement of the volume of fluid dispensed and avoid inoperabilityand/or component damage at low temperatures. Moreover, the system may beused to sell fluid at a specific temperature as compensated wholesalesales.

In preferred embodiments described in more detail below, the systemcomprises two subsystems. First, the system preferably comprises atemperature conditioning subsystem inline to the fluid flow path at alocation upstream of a flow meter. This subsystem may comprise either orboth of a heating device and a cooling device. Second, the systempreferably comprises a recirculation subsystem to recirculate the fluidthrough the dispenser and/or back to a storage tank. The recirculationmay be continuous or intermittent, and in some embodiments the internaldispenser piping may be evacuated to prevent freezing. However,depending on the climate at the location of the fluid dispenser, thetype of fluid dispensed, and the needs of an operator, the recirculationsubsystem may not be provided. For example, where the cooling device isneeded to lower the temperature of the fluid dispensed, the fluiddispenser may not include a recirculation subsystem. This could be thecase in some warmer climates where liquid fuel is dispensed.

More specifically, FIG. 4 shows a fluid temperature conditioning andcontrol system in accordance with one embodiment of the presentinvention. Fluid dispenser 200 is preferably adapted to dispense eitherliquid fuel or DEF and comprises a housing 202 with a coaxial fluid hose204 extending therefrom. Hose 204 terminates in a manually-operatednozzle 206 adapted to be inserted into a vehicle's fuel or DEF tank. Asexplained above, those of skill in the art will appreciate that thematerials used in constructing the fluid handling components (includinghose 204 and nozzle 206) of dispenser 200 may depend on whether liquidfuel or DEF will be dispensed.

Fluid dispenser 200 comprises a control system 208 which is preferablypositioned in an electronics compartment 210. As described in moredetail below, in this embodiment control system 208 controls the fluidtemperature conditioning aspects of the present invention. Controlsystem 208 preferably also controls various other functions of fluiddispenser 200, such as valves, displays and the like, as is wellunderstood. Control system 208 may preferably be communicatively coupledto a site controller 212, for example by a suitable dispensercommunication network 214.

Generally, an STP 216, which is preferably analogous to STP 32, isassociated with a UST 218 containing fluid 220 to pump fluid 220 along afluid flow path to fluid dispenser 200 for eventual delivery. However,as explained above, in alternative embodiments an above-ground storagetank may be provided and/or a dry-pit pump may be used to pump fluid 220to the fluid dispenser 200. In addition, fluid 220 may preferably beeither liquid fuel or DEF. Additionally, in some embodiments fluiddispenser 200 may be self-contained, meaning fluid 220 is drawn to thefluid dispenser 200 by a pump 221 controlled by a motor positionedwithin housing 202. Those of skill in the art will appreciate that whereSTP 216 is used to pump fluid 220, pump 221 may not be provided.

Fluid 220 flowing through main fluid piping 222 enters housing 202 andfirst encounters a fluid temperature conditioning subsystem 224. In someembodiments, main fluid piping 222 may be double-walled and may beabove- or below-ground. Also, those of skill in the art will appreciatethat where main fluid piping 222 is provided below-ground, main fluidpiping 222 and any associated valves or manifolds are typically buriedbelow the “frost line.” Further, in some embodiments, main fluid piping222 may first enter housing 202 via a shear valve analogous to shearvalve 46. Temperature conditioning subsystem 224, which in this case ispositioned in a fluid handling compartment 226 of fluid dispenser 200,is adapted to condition the fluid to maintain it at a desiredtemperature. In preferred embodiments, temperature conditioningsubsystem 224 may comprise a heating device 228 and/or a cooling device230, each in electronic communication with control system 208. This maybe accomplished via communication line 231.

As explained above, fluid temperature conditioning subsystem 224 mayperform several functions. For example, it may condition liquid fuel orDEF to a predetermined temperature upstream of a flow meter 234 tofacilitate accurate volumetric measurement. Also, it may condition DEFto prevent the DEF from crystallizing and freezing at low temperatures.

Although fluid temperature conditioning subsystem 224 is illustrated inFIG. 4 internal to fluid handling compartment 226, those of skill in theart will appreciate that fluid temperature conditioning subsystem 224may be located at any location along the path of fluid flow between UST218 and nozzle 206. In some embodiments, for example, temperatureconditioning subsystem 224 may be located in UST 218 and providetemperature conditioning functionality for a plurality of fluiddispensers 200 located at a retail service station. However, temperatureconditioning subsystem 224 is preferably located immediately upstream offlow meter 234 so that meter 234 may measure the fluid 220 at a constanttemperature and volume.

Heating device 228 is preferably an electrical, on-demand heatersituated in-line to the fluid flow path. A suitable heating device isselected based on various factors, such as the type of fluid dispensed,the location of the heating device along the fluid flow path, and theambient temperatures to which the fluid dispenser is exposed, amongother factors. Many different types of devices may be used for heatingdevice 228, including tubular, immersion, circulation, and impedanceheaters.

However, in preferred embodiments, heating device 228 may be aninduction heater. Induction heaters have several desirablecharacteristics. For example, induction heaters provide for precisetemperature control and rapid adjustment of temperature. In addition,heat is provided uniformly along the length of the pipe being heated.Induction heaters may be used to heat a conductive pipe by subjectingthe pipe to a time-varying magnetic field which surrounds a coilcarrying high frequency alternating current. Heating of the pipe occursvia the electrical resistance of the pipe and, where the pipe is formedof a magnetic material, hysteresis losses.

Several induction heating arrangements are possible. The coil istypically provided having one or more windings surrounding the sectionof the pipe to be heated. Often, the coil is formed of copper tubing andmay be cooled by circulating water therethrough. In this arrangement,the pipe is heated via resistance and hysteresis losses and heat isconducted to the fluid flowing in the pipe. However, in alternativeembodiments, a magnetic wire may be provided internal to a nonconductiveconduit or hose in the fluid flow path. The coil again has one or morewindings surrounding the section of the conduit to be heated. In thiscase, however, the conduit itself is not heated. Instead, the wiregenerates heat via electrical resistance and hysteresis losses and heatis conducted to the fluid in the conduit.

Cooling device 230 is also situated in-line to the fluid flow path.Cooling device 230 preferably comprises a suitable on-demandrefrigeration system. For example, cooling device 230 may comprise aclosed-circuit vapor-compression refrigeration system. Alternatively, aheat exchanger suitable for cooling fluid flowing in a pipe may be used,such as a shell and tube or plate and fin heat exchanger.

Depending on the fluid dispensed and the environment in which fluiddispenser 200 operates, those of skill in the art will appreciate thateither heating device 228 or cooling device 230 may not be provided intemperature conditioning subsystem 224. For example, cooling device 230is not typically provided if fluid dispenser 200 dispenses DEF. Further,where both devices are provided, heating device 228 and cooling device230 may be arranged in the fluid flow path in any order.

Control system 208 is adapted to selectively operate temperatureconditioning subsystem 224 based on the temperature of fluid 220 and theambient temperature. (Typically, both devices 228, 230 will not beoperating simultaneously.) Thus, control system 208 is preferably inelectronic communication with one or more thermometric probe located atvarious locations along the fluid flow path and associated with fluiddispenser 200, such as thermometric probe 235. Although not shown inFIG. 4, those of skill in the art will appreciate that the one or morethermometric probes may communicate with control system 208 via suitablecommunication lines. Thermometric probes may preferably be provided atleast in the UST 218, dispenser sump 236, and flow meter 234. Controlsystem 208 receives temperature information from the thermometric probesand determines whether the temperature of the fluid needs to beconditioned. For example, when the ambient temperature falls below apredetermined level, control system 208 may determine that fluid 220should be heated to prevent freezing. Alternatively, when temperaturesare at a suitable level, temperature conditioning subsystem 224 is notoperated and fluid 220 will simply flow through subsystem 224 withoutbeing conditioned.

In many embodiments, fluid leaving temperature conditioning subsystem224 next encounters flow meter 234. Flow meter 234 may be any suitableflow meter for fluid dispensing, but meter 234 may preferably be apositive displacement or inferential flow meter. Other types of flowmeters are contemplated, however, including Coriolis mass flow meters.Meter 234 is preferably analogous to meter 52, and thus it may comprisea pulser in electronic communication with control system 208.

After the fluid 220 exits the outlet of flow meter 234, it flows throughinternal fluid piping 238 to a flow control valve 240 and a flow switch242. Flow control valve 240 may be a proportional solenoid valveanalogous to flow control valve 50 and may preferably be located below avapor barrier 244. In some embodiments, flow control valve 240 may belocated upstream of flow meter 234. Flow switch 242, which is preferablyanalogous to flow switch 70, is preferably a one-way check valve thatprevents rearward flow through fluid dispenser 200. As with flow controlvalve 50 and flow switch 70 above, flow control valve 240 and flowswitch 242 are in electronic communication with control system 208 toallow fluid dispensing and communicate when fluid is flowing throughflow meter 234.

Fluid 220 exiting flow switch 242 is carried via internal fluid piping238 to a flow manifold 246. Manifold 246 is fluidly coupled to internalfluid piping 238 and fluid dispensing hose 204 to direct fluid 220 fromflow switch 242 to hose 204. In many embodiments, fluid dispenser 200 isnot adapted for vapor recovery. Nevertheless, hose 204 may preferablycomprise concentric outer hose 248 and inner hose 250, which define afluid delivery line 252 and a fluid return line 254. As explained inmore detail below, coaxial fluid hose 204 facilitates recirculation offluid, such as when fluid dispenser 200 is not in use. Those of skill inthe art will appreciate that where it is desirable that fluid dispenser200 be adapted for vapor recovery, for example where fluid 200 is liquidfuel, a three-channel hose may be provided.

Internal fluid piping 238 is fluidly coupled to fluid delivery line 252at manifold 246. Thus, after flowing through manifold 246, fluid 220passes through fluid delivery line 252 of fluid hose 204 to nozzle 206for delivery to a customer's vehicle. To initiate fluid flow, thecustomer manually activates a trigger on fluid nozzle 206 which opens adispensing valve in nozzle 206 so that fluid is dispensed into thevehicle. Manifold 246 also provides a fluid coupling between fluidreturn line 254 and internal fluid return piping 256, which may bedouble-walled. As explained in more detail below, this couplingfacilitates recirculation of fluid 220 through dispenser 200 or returnof fluid 220 to UST 218.

In this regard, in one embodiment of the present invention, arecirculation subsystem may cooperate with fluid temperatureconditioning subsystem 224 to condition the fluid 220. Specifically, therecirculation subsystem comprises a one-way bypass valve 257 situated atthe distal end of fluid return line 254 of fluid hose 204, which isconnected to nozzle 206. The bypass valve 257, which may be a springloaded poppet valve, is biased to close fluid return line 254 duringfluid dispensing, when the fluid pressure in nozzle 206 and fluid hose204 is relatively low.

The recirculation subsystem also comprises a second bypass valve 258located downstream of manifold 246 in the fluid return path alonginternal fluid return piping 256. Second bypass valve 258 may preferablybe a solenoid-controlled valve in electronic communication with controlsystem 208 via communication line 259. In this embodiment, valve 258 islocated in fluid handling compartment 226, but those of skill in the artwill appreciate that it may be located at any point downstream ofmanifold 246 along the fluid return path to UST 218. Second bypass valve258 is normally in the closed position when the recirculation subsystemis not in use.

Finally, the recirculation subsystem comprises main fluid return piping260, which may be double-walled. In some embodiments, main fluid returnpiping 260 may be fluidly coupled to internal fluid return piping 256via a shear valve, as described above. Main fluid return piping 260 isin fluid communication with UST 218, extending from housing 202 throughdispenser sump 236 and STP sump 262. Thus, as described below, in thisembodiment fluid 220 may be continuously recirculated back to UST 218 tomaintain the temperature of fluid 220 when not being dispensed.

In operation, once dispensing is complete, the customer manuallyreleases the trigger on nozzle 206 and its internal dispensing valvecloses. Normally, at this point control system 208 closes flow controlvalve 240 to stop the flow of fluid to nozzle 206. However, if controlsystem 208 determines that the temperature of the fluid 220 and/or theambient temperature is below a predetermined level, it will activate therecirculation subsystem of the present invention. Specifically, in thisembodiment, control system 208 allows the flow control valve 240 toremain open, causing fluid pressure to build in nozzle 206 and fluidsupply line 252. As a result, the one-way valve 257 in fluid return line254 opens and fluid 220 will enter fluid return line 254.

Control system 208 also causes second bypass valve 258 to open, andfluid 220 flows from fluid return line 254 through manifold 246,internal fluid return piping 256, and main fluid return piping 260.Finally, fluid 220 is returned to UST 218. Therefore, the recirculationsubsystem will maintain the temperature of the fluid 220 and may improvethe flexibility of hose 204 at low temperatures. Those of skill in theart will appreciate that continuous recirculation of fluid 220 may besufficient to prevent freezing of fluid 220, in which case temperatureconditioning subsystem 224 would not be operated. However, in colderclimates it is contemplated that temperature conditioning subsystem 224may operate in conjunction with the recirculation subsystem. Controlsystem 208 will continue to operate the recirculation subsystem untildispensing is resumed or it determines that the fluid and/or ambienttemperatures have risen to an acceptable level. When either eventoccurs, control system 208 will cause flow control valve 240 and secondbypass valve 258 to close.

FIG. 5 provides a schematic illustration of a fluid temperatureconditioning and control system according to an alternative embodimentof the present invention. The fluid dispensing system illustrated inFIG. 5 is in many respects identical to the fluid dispensing systemillustrated in FIG. 4. However, in this embodiment, once fluiddispensing is complete, fluid 220 recirculates through fluid dispenser200 instead of returning to UST 218.

In particular, the recirculation subsystem illustrated in FIG. 5comprises the bypass valve 257 in fluid return line 254 described aboveand a second bypass valve 264, which is preferably analogous to valve258. Thus, valve 264 is in electronic communication with control system208 via communication line 265. However, valve 264 may be locatedupstream of a fluid recirculation pump 266. Valve 264 is normally in theclosed position when the recirculation subsystem is not in operation.Recirculation pump 266 is in electronic communication with controlsystem 208 via communication line 267. In some embodiments, pump 266 maycomprise a controlled valve, in which case second bypass valve 264 maybe unnecessary.

In the recirculation subsystem of this embodiment, main fluid piping 222extends from STP 216 through STP sump 262 and dispenser sump 236 to arecirculation manifold 268. In addition, main fluid piping 222 includesa stop valve 270. A junction (i.e., recirculation manifold 268) fluidlycouples main fluid piping 222 to internal fluid piping 238 and internalfluid return piping 256. Stop valve 270 is in electronic communicationwith control system 208 via communication line 271 and may preferably bea solenoid controlled valve. As described below, stop valve 270 isnormally in the open position.

In operation, once dispensing is complete and control system 208determines that temperatures are below a predetermined level, it willactivate the recirculation subsystem. Control system 208 again allowsflow control valve 240 to remain open so that fluid 220 will enter fluidreturn line 254. Control system 208 causes second bypass valve 264 toopen and stop valve 270 to close, thus trapping fluid 220 in arecirculation loop. Control system 208 also activates recirculation pump266 to cause fluid 220 to recirculate through fluid dispenser 200.Temperature conditioning subsystem 224 typically operates in conjunctionwith the recirculation subsystem to heat the fluid 220 as it flows alongthe fluid flow path, as needed.

As explained above, this recirculation will continue until dispensing iscommenced or fluid and/or ambient temperatures reach a predeterminedthreshold. Upon occurrence of either event, control system 208 causesbypass valve 264 to close, deactivates pump 266, and causes stop valve270 to open. Where the temperatures reach the predetermined thresholdbut dispensing is not desired, control system 208 may additionally causeflow control valve 240 to close.

FIG. 6 provides a schematic illustration of a fluid temperatureconditioning and control system according to a second alternativeembodiment of the present invention. The fluid dispensing systemillustrated in FIG. 6 is in many respects identical to the fluiddispensing system illustrated in FIG. 4. However, in this embodiment,once fluid dispensing is complete, fluid 220 is evacuated from fluiddispenser 200 and returned to UST 218. Then, when dispensing is desired,air in the internal fluid piping and fluid handling components of fluiddispenser 200 is removed and the system is primed with fluid.

Those of skill in the art will appreciate that this embodiment may beadditionally useful in the event of a protracted loss of power at fluiddispenser 200. Because fluid 220 is returned to UST 218 when therecirculation subsystem of this embodiment is operated, no fluid 220will remain in the dispenser 200 if power is lost. As a result, thefluid 220 will not freeze inside the dispenser.

In this regard, the recirculation subsystem illustrated in FIG. 6comprises the bypass valve 257 in fluid return line 254 described aboveand a second bypass valve 272, which is preferably analogous to valves258, 264. Valve 272 is in electronic communication with control system208 via communication line 273. Valve 272, which is also normallyclosed, may be located upstream of a fluid recirculation pump 274, whichis preferably analogous to recirculation pump 266. Pump 274 is inelectronic communication with control system 208 via communication line275. In some embodiments, pump 274 may comprise a controlled valve, inwhich case second bypass valve 272 may be unnecessary.

In the recirculation subsystem of this embodiment, main fluid piping 222may extend from STP 216 through STP sump 262 and dispenser sump 236 toan ON/OFF valve 276, which may preferably be a solenoid controlled valvein electronic communication with control system 208 via communicationline 277. It will be appreciated that valve 276 need not be located indispenser sump 236; for example, it may also be located in fluidhandling compartment 226. Main fluid piping 222 is in fluidcommunication with internal fluid piping 238. In this embodiment,internal fluid piping 238 also comprises a fluid inlet 278 and a fluidinlet valve 280. However, those of skill in the art will appreciate thatfluid inlet 278 and fluid inlet valve 280 may be located at otherlocations downstream of valve 276. Valve 280, which is preferably aproportional solenoid controlled valve in electronic communication withcontrol system 208 via communication line 281, is normally in a closedposition. As described below, fluid inlet 278 is adapted to introduce asecond fluid into internal fluid piping 238 as fluid 220 is evacuated.In the illustrated embodiment the second fluid is air, but those ofskill in the art may select other suitable evacuation fluids, such as aninert gas or the like.

In operation, once dispensing is complete and control system 208determines that the fluid and/or ambient temperatures have fallen belowa predetermined threshold, control system 208 activates therecirculation subsystem. Control system 208 again allows flow controlvalve 240 to remain open so that fluid 220 will enter fluid return line254. Control system 208 causes ON/OFF valve 276 to close, second bypassvalve 272 to open, and fluid inlet valve 280 to open. Control system 208also activates recirculation pump 274 to evacuate fluid 220 fromdispenser 200. Those of skill in the art will appreciate pumping fluid220 from fluid dispenser 200 while ON/OFF valve 276 is closed creates apressure in internal fluid piping 238 that is lower than the atmosphericpressure, thus drawing air into the fluid dispenser 200's internal fluidpiping and fluid handling components via fluid inlet 278. In thisembodiment, temperature conditioning subsystem 224 is not typicallyoperated as fluid 220 is evacuated.

After all of the fluid 220 has been evacuated from fluid dispenser 200and returned to UST 218, control system 208 deactivates recirculationpump 274. In addition, control system 208 causes fluid inlet valve 280,flow control valve 240, and second bypass valve 272 to close. At thispoint, no fluid 220 remains in fluid dispenser 200; thus, freezing andassociated component damage is not a problem.

When fluid dispensing is desired, a customer removes nozzle 206 from itsnozzle boot. Before dispensing may commence, however, fluid dispenser200 must be primed with fluid 220. Thus, control system 208 causesON/OFF valve 276, flow control valve 240, and second bypass valve 272 toopen. In addition, STP 216 is activated to pump fluid 220 to dispenser200. (Recirculation pump 274 is not typically operated during priming.)Control system 208 may determine that fluid dispenser 200 is primed, forexample, by measuring a predetermined amount of fuel pumped through thesystem using meter 234, waiting a predetermined amount of time prior toallowing fluid dispensing, or receiving a signal from a pressuretransducer. In the latter case, the pressure transducer may preferablybe associated with recirculation pump 274, although other locations forthe pressure transducer along the fluid flow path are contemplated.

As fluid 220 is reintroduced into fluid dispenser 200, fluid 220displaces the second fluid (air, in this example) and causes it to flowto ullage 282 of UST 218. To prevent an undesirable rise in pressure inUST 218, an ullage pressure reducing system may be provided. Suchsystems are well known to those of skill in the art. For example, a ventpipe capped with a pressure relief valve may be fluidly coupled to UST218 and ullage 282. Thereby, the second fluid that is transferred toullage 282 may be safely dissipated to the atmosphere. After controlsystem 208 determines that fluid dispenser 200 is primed with fluid 220,control system 208 causes second bypass valve 272 to close. Finally,control system 208 zeroes the display and allows dispensing to commence.

While one or more preferred embodiments of the invention have beendescribed above, it should be understood that any and all equivalentrealizations of the present invention are included within the scope andspirit thereof. The embodiments depicted are presented by way of exampleonly and are not intended as limitations upon the present invention.Thus, it should be understood by those of ordinary skill in this artthat the present invention is not limited to these embodiments sincemodifications can be made. Therefore, it is contemplated that any andall such embodiments are included in the present invention as may fallwithin the scope and spirit thereof.

What is claimed is:
 1. A fluid dispenser for installation in a forecourtin a fueling environment for dispensing liquid fuel or diesel exhaustfluid from at least one fluid storage tank remote from said fluiddispenser into a vehicle, comprising: a housing in which fluid flowcontrol components are located; at least one fluid conduit completingfirst and second fluid flow paths between said at least one fluidstorage tank and a nozzle coupled to said housing; a fluid flow meterlocated along said first fluid flow path; a control system; and arecirculation subsystem, said recirculation subsystem comprising abypass valve located along one of said first and second flow paths; saidbypass valve being operative to prevent fluid communication between saidfirst and second fluid flow paths when said fluid dispenser is in useand to allow fluid communication between said first and second fluidflow paths when said fluid dispenser is not in use.
 2. A fluid dispenseras in claim 1, further comprising a fluid temperature conditioningsubsystem positioned in said housing, said fluid temperatureconditioning subsystem located along said first fluid flow path upstreamof said fluid flow meter.
 3. A fluid dispenser as in claim 2, whereinsaid fluid temperature conditioning subsystem comprises a heatingdevice.
 4. A fluid dispenser as in claim 2, wherein said fluidtemperature conditioning subsystem comprises a cooling device.
 5. Afluid dispenser as in claim 2, wherein said control system is adapted toselectively operate said fluid temperature conditioning subsystem upondetection of a predetermined temperature.
 6. A fluid dispenser as inclaim 5, wherein said control system is in electronic communication withat least one thermometric probe.
 7. A fluid dispenser as in claim 1,wherein said bypass valve is located at a distal end of one of saidfirst and second fluid flow paths proximate said nozzle.
 8. A fluiddispenser as in claim 1, said recirculation subsystem further comprisingat least one controllable valve, said control system being adapted toselectively actuate said at least one controllable valve such thatflowing fluid flows to said at least one fluid storage tank when saidfluid dispenser is not in use.
 9. A fluid dispenser as in claim 1,further comprising a recirculation pump coupled to one of said first andsecond fluid flow paths.
 10. A fluid dispenser as in claim 9, furthercomprising a fluid inlet along one of said first and second fluid flowpaths for ingress of an evacuation fluid.
 11. A fluid dispenser as inclaim 10, said recirculation subsystem further comprising at least onecontrollable valve, said control system being adapted to selectivelyactuate said at least one controllable valve and said recirculation pumpsuch that fluid is evacuated from said at least one fluid conduit andreturned to said at least one fluid storage tank.
 12. A fluid dispenseras in claim 9, said recirculation subsystem further comprising at leastone controllable valve, said control system being adapted to selectivelyactuate said at least one controllable valve and said recirculation pumpsuch that said liquid fuel or said diesel exhaust fluid recirculatesalong said first and second fluid flow paths through said fluiddispenser without returning to said at least one fluid storage tank. 13.A fluid dispenser as in claim 1, wherein said at least one fluid conduitcomprises first and second fluid conduits.
 14. A fluid dispenser fordispensing liquid fuel or diesel exhaust fluid from at least one fluidstorage tank into a vehicle, comprising: a housing in which fluid flowcontrol components are located; a control system; a first fluid conduitcompleting a first flow path between said at least one fluid storagetank and a nozzle coupled to said housing; a second fluid conduitcompleting a second flow path between said nozzle and said at least onefluid storage tank; a bypass valve located along one of said first andsecond flow paths, said bypass valve being selectively openable to allowfluid communication between said first and second flow paths; and atleast one controllable valve located along said second flow path, saidat least one controllable valve in electronic communication with saidcontrol system.
 15. A fluid dispenser as in claim 14, further comprisinga temperature conditioning subsystem located along said first flow pathupstream of a fluid flow meter located in said housing.
 16. A fluiddispenser as in claim 15, further comprising at least one thermometricprobe along at least one of said first and second flow paths, said atleast one thermometric probe in electronic communication with saidcontrol system.
 17. A fluid dispenser as in claim 16, wherein saidcontrol system is adapted to selectively operate said fluid temperatureconditioning subsystem upon detection of a predetermined temperature.18. A fluid dispenser as in claim 14, further comprising a dual-channelhose extending between said housing and said nozzle, said dual-channelhose defining first and second separate flow channels.
 19. A fluiddispenser as in claim 18, wherein said bypass valve provides fluidcommunication between said first and second flow channels in said hosewhen said bypass valve is open.
 20. A method of measuring the flow rateof a fluid in a fluid dispenser for dispensing liquid fuel or dieselexhaust fluid to a vehicle in a fueling environment, comprising thesteps of: providing a fluid dispenser comprising a housing and a controlsystem; said fluid dispenser defining first and second fluid conduitsconnectable to first and second fluid flow paths, respectively, betweenat least one fluid storage tank and a nozzle coupled to said fluiddispenser; providing a first controllable valve located along said firstflow path and in electronic communication with said control system, saidfirst flow path defining a fluid inlet for an evacuation fluiddownstream of said first controllable valve; providing a recirculationpump coupled to said second flow path and in electronic communicationwith said control system; closing said first controllable valve andevacuating said fluid from said first and second fluid conduits whensaid fluid dispenser is not in use.